"lead-down" >>>> "leak-down" (Ken must have been using my keyboard... it causes all sorts of typos.)

Have you had any incidence of overheating?

In our experience, a blown head gasket is more common compared to the oil cooler seals. 

Perhaps you can try a lead-down test as it may show evidence of a blown head gasket.

If not, you might go ahead and replace the oil cooler seals since it is much cheaper than replacing the head gasket.

Let us know what you find out.
Ken

is the oil cooler paired with your rad?  

I'm getting coolant in my oil.. Is there a way to know if this is a bad head gasket or bad oil cooler? 

2003 MINI Cooper S